This invention generally relates to electrothermal devices which produce an energetic plume. Specifically, an arcjet is disclosed which incorporates any one of several different design features for improved performance. The energetic plume from this type of arcjet can be used to provide thrust in space applications where the arcjet is part of a propulsion system for spacecraft attitude and orbit maintenance and repositioning functions. Similarly, the energetic plume from this type of arcjet can be used for a variety of ground based materials processing purposes.
Arcjets are known. Gas is heated to very high temperatures in an arcjet by heat transfer from a high power density electric arc. Expansion of this gas through a nozzle converts the heat energy in the gas to directed kinetic energy. The energetic arcjet plume can be made to perform useful work by providing thrust in a spacecraft propulsion application, or as a means of energy addition in numerous ground based materials processing applications. For a perspective of methods that have been employed to enhance the operation of arcjets, attention is directed to U.S. Pat. No. 3,016,693 to J. Ro Jack et al., U.S. Pat. No. 3,309,873 to G. L. Cann, U.S. Pat. No. 3,692,431 to R. Gebel, U.S. Pat. Nos. 4,548,033 and 4,577,461 to G. L. Cann, U.S. Pat. No. 4,800,716 to W. W. Smith et al., U.S. Pat. No. 4,805,400 to S. C. Knowles, U.S. Pat. No. 4,882,465 to W. W. Smith et al., U.S. Pat. No. 4,866,929 to S. Knowles et al., U.S. Pat. No. 4,907,407 to M. A. Simon et al., U.S. Pat. Nos. 4,926,632 and 4,995,231 to R. D. Smith et al., U.S. Pat. No. 5,111,656 to M. A. Simon et al., and U.S. Pat. No. 5,319,926 to M. Steenborg.
The prior art arcjet designs and their various embodiments have been intended to improve arcjet performance by better transfer of the arc energy to the flowing propellant gas. However, often times these prior art embodiments have proven to be ineffective in acting in a cumulative manner to significantly improve the overall arcjet performance. The net result is that substantial, across the board, arcjet performance gains have remained an elusive goal.